Manufacturers of foodstuffs, beverages, medicaments, dentifrice and the like are concerned to ensure that products they place on the market are not tampered with before being opened by the ultimate consumer of the goods. For this purpose it has become conventional to include in closures for such goods means which will indicate whether the closure has been tampered with before purchase. In the case of containers having an externally screw threaded neck it is common to provide the closure with a tamper evident band which engages behind a retaining flange formed on the neck of the container. The tamper evident band is joined to a depending skirt forming part of the closure by a number of frangible bridges. On application of the closure to the container the band is forced over the retaining flange, however, when the closure is unscrewed from the container the bridges are sheared as the band is trapped behind the retaining flange while the closure moves up the neck of the container.
While such tamper evident bands have been widely accepted there is a delicate balance between the two conflicting requirements. On the one hand, one must be able to apply the closures to containers at very high speed without inadvertently breaking the bridges, or breaking or deforming the band itself, or deleteriously affecting the seal between the closure and the container. On the other hand, the band must be sufficiently tightly secured behind the retaining flange and the bridges and/or the band must be sufficiently easily broken that the closure cannot be removed from the container without rupturing the bridges and/or the band.
Another problem is that an unauthorized person might attempt to remove the closure and tamper evident band, without damaging the band or frangible bridges, in order to contaminate or replace the container contents and then reapply the closure. Such operation might be attempted with the assistance of a thin device, such as a knife blade, wedged up between the tamper evident band and the neck of the container to which the closure has been applied. The devices might then be levered outwardly in order to expand the inner diameter of the band so that it may be passed back over the retaining flange of the container. In such a process the device will be edged around the circumference of the band so as to gradually ease the band over the retaining flange at a continuously lengthening portion of the band circumference.
Closures of the type mentioned above are used around the world in extremely large numbers. To be commercially acceptable such closures must be capable of being produced very rapidly in automated machinery. This itself may produce a conflict with the functionality of the closure and/or its tamper evident band.
The arrangement according to the present invention is designed to provide the public with an alternative form of closure having a tamper evident band.